package com.dt.module.om.util;

import javax.crypto.Cipher;
import javax.crypto.spec.SecretKeySpec;
import java.security.Key;
import java.security.Security;

public class DES {
    private static String strDefaultKey = "national";

    private Cipher encryptCipher = null;

    private Cipher decryptCipher = null;

    public static String byteArr2HexStr(byte[] arrB) throws Exception {
        int iLen = arrB.length;
        StringBuffer sb = new StringBuffer(iLen * 2);
        for (int i = 0; i < iLen; i++) {
            int intTmp = arrB[i];
            while (intTmp < 0)
                intTmp += 256;
            if (intTmp < 16)
                sb.append("0");
            sb.append(Integer.toString(intTmp, 16));
        }
        return sb.toString();
    }

    public static byte[] hexStr2ByteArr(String strIn) throws Exception {
        byte[] arrB = strIn.getBytes();
        int iLen = arrB.length;
        byte[] arrOut = new byte[iLen / 2];
        for (int i = 0; i < iLen; i += 2) {
            String strTmp = new String(arrB, i, 2);
            arrOut[i / 2] = (byte)Integer.parseInt(strTmp, 16);
        }
        return arrOut;
    }

    public DES() throws Exception {
        this(strDefaultKey);
    }

    public DES(String strKey) throws Exception {
        Security.addProvider(new SunJCE());
        Key key = getKey(strKey.getBytes());
        this.encryptCipher = Cipher.getInstance("DES");
        this.encryptCipher.init(1, key);
        this.decryptCipher = Cipher.getInstance("DES");
        this.decryptCipher.init(2, key);
    }

    public byte[] encrypt(byte[] arrB) throws Exception {
        return this.encryptCipher.doFinal(arrB);
    }

    public String encrypt(String strIn) throws Exception {
        return byteArr2HexStr(encrypt(strIn.getBytes()));
    }

    public byte[] decrypt(byte[] arrB) throws Exception {
        return this.decryptCipher.doFinal(arrB);
    }

    public String decrypt(String strIn) throws Exception {
        return new String(decrypt(hexStr2ByteArr(strIn)));
    }

    private Key getKey(byte[] arrBTmp) throws Exception {
        byte[] arrB = new byte[8];
        for (int i = 0; i < arrBTmp.length && i < arrB.length; i++)
            arrB[i] = arrBTmp[i];
        Key key = new SecretKeySpec(arrB, "DES");
        return key;
    }
}
